Sweep the last three uses of the columns SP8 dropped

`seed_demo.py` still passed `index=0` to `models.Action`, which raises
`TypeError` now that the attribute is gone. Every call site inside `app/`
was updated when the column went, but the seed script sits outside the
package and was missed.

`bundle.settle` wrote `memory_cursor` and `summary_cursor`, which are no
longer mapped, so the assignments only set transient Python attributes.
The version 2 branch existed solely to make those assignments, and it ran
two queries per cursor to do it, so it goes. `settle` now returns early
when the bundle carries anchors. The `db` parameter is unused after that.

Also move the comment about deleted memories next to the
`db.delete(branch)` it describes. Splitting the router package left it
after the `finally`, where it read as attached to nothing.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YFQY6WgaE3JaX3dXkxLynV

backend/app/bundle.py

@@ -587,31 +587,22 @@ def _write_anchors(
         cursor.anchor(adventure, ids[branch] if branch is not None else None, depth)
 
 
-def settle(db: Session, adventure: models.Adventure, story: dict) -> None:
-    """Aligns the two coordinate systems, once the nodes exist.
+def settle(adventure: models.Adventure, story: dict) -> None:
+    """Resolves a version 1 bundle's counts into anchors, once the nodes exist.
 
-    The anchors and the legacy counts describe the same boundary in different
-    terms, and each version of the bundle carries one of them. A version 1 file
-    carries the count, so the anchor is found by counting that far along the
-    story. A version 2 file carries the anchor, so the count is read back from
-    it. The legacy columns are written either way, because a rolled-back build
-    reads them.
+    A version 1 file records how far the memories and the summary have read as
+    a count, so the anchor is found by counting that far along the story. A
+    version 2 file carries the anchor itself, which `_write_anchors` has
+    already stored, so there is nothing left to do.
 
-    The caller runs this after the flush, because both directions need the
-    actions to be queryable.
+    The caller runs this after the flush, because counting needs the actions to
+    be queryable.
     """
     positions = story["positions"]
+    if positions is None:
+        return
     for cursor in cursors.ALL:
-        if positions is not None:
-            setattr(adventure, f"{cursor.name}_cursor", positions[cursor.name])
         cursors.anchor_at_position(adventure, cursor, positions[cursor.name])
-        else:
-            setattr(
-                adventure, f"{cursor.name}_cursor",
-                cursors.position_of(adventure, cursor.depth(db, adventure)),
-            )
-
-
 
 
 def materialize(
@@ -673,7 +664,7 @@ def materialize(
     write(db, adventure, story)
     db.flush()
     db.expire(adventure, ["actions"])
-    settle(db, adventure, story)
+    settle(adventure, story)
     return adventure
 
 # ------------------------------------------------------------------ reading

backend/app/routers/adventures/branches.py

@@ -190,18 +190,15 @@ def delete_branch(
             stored_branch, _ = cursor.stored(adventure)
             if stored_branch in doomed:
                 cursor.clear(adventure)
+        # The deleted branch's memories are deleted with it, and their cached
+        # vectors drop out of the catalogue on the next read, so no
+        # invalidation call is needed. See the note on the `memorybank` cache.
         db.delete(branch)
         adventure.updated_at = models.utcnow()
         db.commit()
     finally:
         turns._active_turns.discard(adventure_id)
 
-
-    # The deleted branch's memories are deleted with it, and their cached
-    # vectors drop out of the catalogue on the next read, so no invalidation
-    # call is needed. See the note on the `memorybank` cache.
-
-
 def _branch_subtree(
     db: Session, adventure: models.Adventure, root: models.Branch
 ) -> set[int]:

backend/seed_demo.py

@@ -252,7 +252,7 @@ try:
     for position, s in enumerate(SCRIPTS):
         db.add(models.AdventureScript(adventure_id=adventure.id, position=position, **s))
     opening = models.Action(
-        adventure_id=adventure.id, index=0, type="start", text=scenario.prompt
+        adventure_id=adventure.id, type="start", text=scenario.prompt
     )
     # Through the same door create_adventure uses, so the seeded adventure has a
     # story tree like every other one.